Boiler Replacement Cost UK – 2026 Price Guide
How much does a new boiler cost in the UK in 2026? This guide uses real pricing data from 519 UK towns to show realistic figures for combi, system and regular boiler installations — with Worcester Bosch, Vaillant and Ideal pricing, swap-only vs full-rework costs, and what the £7,500 Boiler Upgrade Scheme (BUS) grant means if you're considering a heat pump instead.
How much does a new boiler cost in the UK? The average boiler replacement cost in 2026 is £2,000–£3,500 supplied and fitted. A like-for-like A-rated combi swap starts around £1,800, a system or regular boiler is £2,300–£3,500, and converting to a combi £3,000–£4,500.
By home size: a 1–2 bed needs a ~24–30kW combi (£1,800–£2,800), a 3-bed semi ~30–35kW (£2,200–£3,200), a 4+ bed ~35kW+ or a system boiler (£2,800–£4,500). New boilers usually come with a 7–12 year warranty.
Do you need planning permission for this?
Boiler swaps don't usually need planning permission, but external flues in conservation areas, wall-mounted units on listed buildings, and air source heat pumps under MCS often need formal approval.
Read the boiler replacement planning rules →Boiler Replacement Cost at a Glance
Typical 2026 UK prices for the three main boiler types installed by Gas Safe engineers. Prices shown are fully installed (like-for-like swap) including flue, system flush and commissioning. Expect 15–25% more if you're changing boiler type or relocating.
All-in-one unit, no tanks. Cheapest option, 1-day install. Good for small-to-medium homes. Worcester Bosch, Vaillant, Ideal most common.
Get quotes →Runs a hot water cylinder for better simultaneous hot water flow. Mid-tier cost. 1–2 day install. Good for larger families.
Get quotes →Traditional hot water cylinder plus cold water tank in loft. Most complex install. 1–2 days. Typical for period properties.
Get quotes →Boiler cost depends on size (kW output), brand, warranty length and whether you're swapping like-for-like or upgrading the system. A Gas Safe engineer will survey your home and spec the right unit.
Get free quotes →Boiler Replacement Cost by Type & Brand (UK 2026)
| Boiler Type & Brand | Model | Installed Cost | Warranty |
|---|---|---|---|
| Combi — Worcester Bosch | Greenstar 30Si (30kW) | £2,400 – £3,200 | 10 years |
| Combi — Vaillant | ecoTEC plus 832 (32kW) | £2,200 – £3,100 | 10 years |
| Combi — Ideal | Logic Max C30 (30kW) | £2,000 – £2,700 | 10 years |
| Combi — Baxi | 800 Combi 2 30kW | £1,900 – £2,600 | 10 years |
| System — Worcester Bosch | Greenstar 27i System | £2,700 – £3,900 | 10 years |
| System — Vaillant | ecoTEC plus 630 | £2,500 – £3,600 | 10 years |
| System — Ideal | Logic Max System S24 | £2,400 – £3,400 | 10 years |
| Regular — Worcester Bosch | Greenstar 30Ri (30kW) | £2,500 – £3,800 | 10 years |
| Regular — Vaillant | ecoFIT pure 430 | £2,400 – £3,500 | 10 years |
| Air Source Heat Pump | 7kW (alternative) | £8,000 – £14,000 | 7 years |
| Boiler + smart thermostat | Nest / Hive / tado° | +£180 – £350 | 2–5 years |
| Powerflush (if needed) | Full system clean | +£400 – £700 | — |
All figures include boiler, flue, system flush, Gas Safe registration, Benchmark commissioning and VAT. Same-day installs typical for like-for-like swaps. Add £400-£1,200 for moving boiler location, or £600-£1,500 for upgrading pipework to 22mm for higher flow.
What's Included in a Boiler Installation Quote
A like-for-like combi boiler swap is one of the cleaner installs in the trade — most of the cost is the boiler itself plus 1 day of labour. Brand and kW output drive the biggest price variance.
Hardware (~60%)
- Boiler unit — £900–£2,200 (varies by brand, output, warranty)
- Flue kit — £120–£280
- Magnetic filter (MagnaClean / Adey) — £80–£180 (required by some warranties)
- Programmable thermostat — £100–£250
- New gas valve / isolators — £40–£80
- Pipe, fittings, insulation — £80–£150
Labour & Services (~40%)
- Gas Safe engineer — £500–£900 (1-day install)
- System flush — £80–£200 (chemical); £400+ (powerflush)
- Gas Safe + Benchmark cert — included
- Building Regs notification — included via Competent Person Scheme
- Old boiler removal + disposal — £80–£150
- Warranty activation — included (10-year Worcester/Vaillant)
Boiler Install Cost by UK Region (Combi, Like-for-Like)
Moderate regional variation — units are nationally priced; labour is where the difference shows.
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Worcester Bosch vs Vaillant vs Ideal vs Baxi vs Viessmann: UK 2026 Boiler Prices
The five biggest boiler brands serving UK homes in 2026 differ noticeably on price, warranty length, parts availability and engineer call-out network. Worcester Bosch is the UK market leader with the largest installer base; Vaillant is the German engineering choice; Ideal is the budget-mid range value pick; Baxi is the long-time reliability bet; Viessmann is the premium energy-efficient option. Below is the verified Q3 2026 brand-by-brand comparison.
| Brand | Combi Boiler Trade Price | Typical Installed (3-bed) | Warranty | Strength |
|---|---|---|---|---|
| Worcester Bosch (Greenstar i / 8000) | £700-1,800 | £2,200-3,800 | 10-12 years (with Accredited Installer) | UK leader, parts everywhere, biggest installer network |
| Vaillant (ecoTEC plus, ecoFIT pure) | £750-1,900 | £2,300-3,900 | 10 years (Advance Installer) | German engineering, quietest in class, hydrogen-ready |
| Ideal (Logic / Vogue) | £550-1,450 | £1,900-3,200 | 7-10 years | Best price/spec ratio, easy install, made in UK |
| Baxi (800 / Platinum+ / EcoBlue+) | £650-1,650 | £2,000-3,400 | 7-10 years | Reliable workhorse, strong UK heritage, hydrogen-ready |
| Viessmann (Vitodens 050 / 100 / 200) | £900-2,400 | £2,500-4,500 | 10-12 years | Best efficiency (94%+), premium engineering, eco-focused |
Trade prices via Gas Safe registered installer accounts (typically 30-45% below RRP showroom). Installed prices include boiler, flue, controls, system filter, scale reducer and 1 day of installation labour. Add £400-900 for power-flush, £200-500 for new gas pipe, £300-700 for smart thermostat upgrade.
Combi vs System vs Heat-Only Boiler: Which Is Right for Your UK Home in 2026?
UK domestic boilers come in three types: combi (most common, instant hot water), system (with hot water cylinder), and heat-only/conventional (cylinder + cold tank in loft). The right type depends on your hot water demand, water pressure, available space and existing pipework.
| Boiler Type | Best For | Typical Installed Cost 2026 | Pros | Cons |
|---|---|---|---|---|
| Combi | 1-2 bathrooms, 1-4 occupants, good mains pressure | £1,900-3,800 | Compact, no cylinder, instant hot water, energy-efficient | Limited flow rate, weak with multiple simultaneous taps |
| System (with unvented cylinder) | 2-3 bathrooms, 3-6 occupants, family homes | £2,800-4,800 | Strong flow at multiple outlets, no cold loft tank | Needs space for cylinder, recovery time after large draws |
| Heat-Only / Conventional | Older homes with existing tank-fed pipework, low mains pressure | £2,200-3,900 | Suits low-pressure systems, simple replacement | Loft tank required, lower efficiency, more components to maintain |
Combi covers ~70% of UK new installs in 2026. System is preferred for family homes with 2+ bathrooms. Heat-only is mostly used for like-for-like replacement in older properties where switching to combi would require extensive pipework changes.
Boiler Replacement Cost by House Size: What kW Do You Need?
Boiler output is rated in kW. Under-sizing leaves you with weak heating; over-sizing wastes gas. Below is the 2026 sizing + installed-cost guide by property size and bathroom count.
| Property | Bathrooms | Recommended Type + kW | Mid-Range Installed 2026 |
|---|---|---|---|
| Flat / 1-bed | 1 | Combi 24-28 kW | £1,900-2,800 |
| 2-bed terrace / flat | 1 | Combi 28-30 kW | £2,000-3,000 |
| 3-bed semi (typical UK home) | 1-2 | Combi 30-35 kW | £2,200-3,500 |
| 4-bed detached | 2 | Combi 35-40 kW or System 24 kW | £2,500-4,200 |
| 5-bed family home | 2-3 | System 28-32 kW + 200L cylinder | £3,200-4,800 |
| 6+ bed / large home | 3+ | System 32-42 kW + 250-300L cylinder | £4,000-6,500 |
Combi DHW flow rate matters at higher kW: 30 kW combi delivers ~12 L/min, 35 kW ~14 L/min, 40 kW ~16 L/min. London/SE add 15-20% on labour. Hydrogen-ready boilers (Vaillant ecoTEC plus, Worcester Lifestyle Plus, Baxi 800) +£100-250 over standard.
Boiler Lifespan + Heat Pump Alternative: Is Replacement Worth It in 2026?
A modern condensing boiler installed in 2026 should last 12-18 years with annual servicing. A 10-year-old boiler is typically running at 80-85% efficiency vs ~94% for a current-generation unit. If it is still fairly young and the fault is minor, it can be worth weighing a fix against a full swap first - our guide to boiler repair costs helps you judge when a repair still makes sense. The big question in 2026 is whether to replace with another gas boiler or move to an air-source heat pump (BUS grant £7,500 available through March 2028). Note that the Boiler Upgrade Scheme covers heat pumps and biomass only — a like-for-like gas boiler carries no grant.
Replace Like-for-Like (Gas Boiler)
Upfront cost: £1,900-4,800 installed
Annual running cost: £850-1,400 (3-bed home, gas at 6.8p/kWh 2026)
Lifespan: 12-18 years
Pros: Lower upfront, fits existing system, no internal disruption
Cons: Running cost tracks wholesale gas prices; carbon footprint higher than a heat pump
Switch to Air-Source Heat Pump
Upfront cost: £8,000-14,000 installed (minus £7,500 BUS grant = £500-6,500 net)
Annual running cost: £700-1,300 (3-bed, electricity at 27p/kWh, COP 3.0-3.5)
Lifespan: 15-20 years
Pros: 3-4x more efficient, grant available, future-proofs your home, lower CO2
Cons: Often needs radiator upgrade (£1,500-3,000), needs well-insulated home, external unit
2026 verdict: If your boiler is 12+ years old and works fine, get it serviced and re-evaluate in 2 years. If it's failing and your home has reasonable insulation (EPC C or better, cavity walls insulated), the BUS-grant heat pump option is now genuinely competitive. If your home is poorly insulated or gas-only listed, a high-efficiency Worcester Bosch / Vaillant combi remains the most pragmatic choice.
Heat Pumps, the Boiler Upgrade Scheme and 0% VAT: 2026 Grant Rules
One point trips up a lot of homeowners: there is no grant for a like-for-like gas boiler. The Boiler Upgrade Scheme (BUS) is a low-carbon heating grant, so it only applies if you switch away from gas. If you replace one gas combi with another, you pay the full installed price shown above — the grants below are only relevant when you are weighing up a heat pump instead.
- BUS grant of £7,500 towards an air-source or ground-source heat pump, or £5,000 towards a biomass boiler in eligible rural properties. Gas, oil and LPG boilers are not eligible.
- EPC precondition removed. Since spring 2026 you no longer need to clear outstanding loft or cavity-wall insulation recommendations on your EPC before applying — a change that opened the grant up to many older homes.
- 0% VAT on the supply and installation of heat pumps and other qualifying energy-saving measures runs until 31 March 2027, after which the rate is due to return to 5%.
- Your installer applies, not you. An MCS-certified installer claims the BUS grant and deducts it from your quote, so the £8,000–£14,000 headline install typically nets £500–£6,500 once the £7,500 is applied.
Full eligibility and the current grant values are set out on the government's own page, gov.uk: Apply for the Boiler Upgrade Scheme — worth reading before you commit either way. If a heat pump means upgrading radiators or pipework, budget separately for that and see our central heating installation cost guide for the wider system picture.
How to Hire a Boiler Installer: Your 2026 Gas Safe Checklist
Any gas boiler work in the UK is legally notifiable and must be carried out by a Gas Safe registered engineer — it is a criminal offence for anyone not on the register to work on your gas appliances. Vetting is on you as the customer, so run through this checklist before you accept a quote and again on the day.
- Check the Gas Safe card and the register. Ask to see the engineer's Gas Safe ID card, then confirm the licence number and the gas types they are qualified for on the free Gas Safe Register. The card alone is not proof — always cross-check the number.
- Insist on an itemised quote. A fair quote lists the boiler model and kW output, the flue kit, a magnetic system filter, controls or thermostat, the flush type (chemical or power flush), making-good and old-boiler removal as separate lines — not a single lump sum.
- Match the boiler to the home, not the other way round. A 3-bed semi with one bathroom rarely needs more than a 30–35 kW combi; jumping to a 40 kW unit, or to a system boiler and cylinder, only makes sense when two or more bathrooms draw hot water at once.
- Get the paperwork. On completion you should receive the Benchmark commissioning certificate and a Building Regulations compliance notification, which a Competent Person Scheme installer files for you — keep both for warranty and resale.
- Be wary of the cheapest quote. A price £500 below the rest usually means a smaller boiler, a shorter warranty, a skipped filter or no flush — any of which can void the manufacturer's guarantee.
Once the job is done, book an annual service to keep the warranty valid and efficiency high, and keep every certificate together for when you come to sell. If a radiator stays cold or the system loses pressure later on, our guide to central heating repair costs covers the common fixes so you know a fair price before calling anyone out.
Boiler Replacement Costs by Town
Each town page shows local boiler engineers, town-specific cost ranges, recent project examples and nearby areas. Compare 3 free quotes from vetted local boiler installers — and always check any engineer's Gas Safe registration on the Gas Safe Register before work starts.
Boiler Replacement Costs at a Glance: 2026 Visual Guide
The biggest single driver of your final bill is the type of job, not the badge on the box. A straight like-for-like combi swap is a one-day visit and the cheapest route; the moment a cylinder, loft tank or a change of boiler position is involved, extra labour days push the price up. Here is how the four common 2026 job types compare on installed cost, using this guide’s verified Q3 2026 ranges.
A proper quote is never just “boiler plus labour”. When you compare three quotes line by line, check every item below is present and priced — a missing magnetic filter or system flush can invalidate a 10-year warranty, and Building Regs notification must come through the engineer’s Competent Person Scheme registration, not be left to you. This is what a compliant 2026 installation quote should cover.
Efficiency is where an ageing boiler quietly costs you. A 10-year-old unit typically runs at 80–85% efficiency, so up to a fifth of the gas you pay for is lost up the flue, while a current A-rated condensing boiler converts around 94% into usable heat. On this guide’s typical 3-bed running costs, that gap is worth roughly £155 a year — every year the old unit stays on the wall.
Combi swap, system, heat-only or a regular-to-combi conversion — each is priced differently. Our new guide breaks down new boiler costs by type and house size, including what an installer’s quote should itemise.
Worcester Bosch, Vaillant, Ideal, Baxi or Viessmann — we compare installed prices, warranty cover and who each suits in our guide to the best boiler brands in the UK. And before you book anyone, read how to choose a boiler installer and the building regs that apply.
Boiler Brand, Type and Replacement FAQs
A mid-range 30kW combi boiler (Worcester Bosch Greenstar, Vaillant ecoTEC or Ideal Logic Max) costs £2,000–£3,200 fully installed in a like-for-like swap on a 3-bed home in 2026. Budget brands (Baxi, Alpha, Glow-worm) run £1,800–£2,500; premium brands (Viessmann Vitodens) £3,000–£4,500. Add £400–£1,200 if you're relocating the boiler or upgrading pipework.
Combi boilers are best for small-to-medium homes (1-2 bathrooms) — cheapest to install, no tanks, instant hot water. System boilers suit larger homes (2-3 bathrooms) where multiple taps/showers run at once — they use a hot water cylinder for better flow. Regular (conventional) boilers are usually retained in period properties with existing cylinders and cold water tanks. The right answer depends on your home size, bathrooms, water pressure and existing system.
In 2026, the £7,500 Boiler Upgrade Scheme (BUS) grant makes an air source heat pump £8,000–£14,000 installed — roughly £500–£6,500 net after the grant for a typical install. Heat pumps work best in well-insulated homes with larger radiators or underfloor heating. If radiators or pipework need upgrading, factor that in early - see typical underfloor heating costs - and check exactly what funding you can claim in our guide to heat pump grants in the UK before you decide. Running costs are typically 30–50% lower than gas at 2026 electricity prices. If you're committed to decarbonising, a heat pump is often the better long-term choice.
Not always — but most manufacturers (Worcester Bosch, Vaillant, Ideal) require proof of flushing to validate warranty. A chemical flush (£80-£200) is sufficient for most installs; a full powerflush (£400-£700) is needed if your system is sludgy, has cold radiators, or has visible corrosion. Ask your engineer to assess — many include a chemical flush as standard and only upsell powerflush if needed.
A straightforward like-for-like combi swap typically takes 1 day (6-9 hours on-site). Changing boiler type (e.g. regular to combi) or relocating adds 1-3 days. System boiler installs with a new cylinder typically take 2 days. Heat pump installs take 2-5 days depending on radiator sizing and outdoor unit positioning.
Variance comes from: brand and model (Worcester Bosch vs Baxi), kW output (24kW vs 30kW vs 35kW), warranty length (7 vs 10 vs 12 years), whether a magnetic filter is fitted, whether a smart thermostat is included, flush type, and whether the installer is on the manufacturer's approved list (which extends warranties by 2-3 years at no cost). Cheap quotes often use a smaller boiler, shorter warranty, budget thermostat or skip the filter.
Yes. The UK government's plan to ban new gas boilers in new-build homes from 2025 has been delayed; there's currently no confirmed ban date for replacement boilers in existing homes. You can install a new gas boiler in 2026 without restriction. That said, trends are clear — BUS grants and energy prices increasingly favour heat pumps. If your current boiler has 2-5 years left, it may be worth waiting for heat pump prices to fall further; if it's failing now, a new gas boiler is a sensible bridge for the next 10-15 years.
Boiler brands compared: Worcester Bosch, Vaillant, Ideal, Baxi, Viessmann and Glow-worm
Six brands account for most UK domestic installs. The differences that matter to a homeowner are warranty length, how easily an engineer gets parts, and whether your installer is accredited to give you the longer warranty in the first place.
| Brand | Known for | Ranges you will be quoted | Typical boiler price | Worth knowing |
|---|---|---|---|---|
| Baxi | Widely stocked; simple to service | Baxi 800, Baxi 600, Platinum+ | £700–£1,350 | Parts are easy to source, which shortens breakdown repairs |
| Glow-worm | Budget end of the Vaillant group | Energy, Betacom, Ultimate | £600–£1,100 | Shares parts with Vaillant, which helps availability |
| Ideal Heating | Value-led, made in Hull | Logic Max, Vogue Max, Logic Combi | £700–£1,400 | Logic Max often carries a long warranty at a mid-market price |
| Vaillant | Quiet, well-built, strong trade following | ecoTEC plus, ecoTEC exclusive, ecoFIT pure | £850–£1,800 | ecoTEC exclusive has a wide modulation range, which suits smaller homes |
| Viessmann | German engineering, stainless heat exchanger | Vitodens 050-W, Vitodens 100-W, Vitodens 200-W | £900–£2,000 | Fewer UK installers carry it, so get more than one quote |
| Worcester Bosch | The UK default; huge installer base | Greenstar 4000, Greenstar 8000 Life, Greenstar CDi | £900–£1,900 | Longest warranties go to Worcester Accredited Installers — ask before you book |
Prices above are for the boiler only — fitting is separate and is priced in the table further up this page. Brands are listed alphabetically, not ranked: BestBuilders does not sell or endorse any of them.
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New boiler & replacement — guides and detail
The detail behind the number: what changes the price, the planning position, and how to check a quote before you accept it.
Registered members: Boilers & Central Heating
9 businesses offering boilers & central heating have a public profile with BestBuilders. Each listing is a business that registered with us directly; the details shown are the ones it declared at registration, and a Companies House number appears only where one was given.
GSB Midlands✓ Companies House number given · ✓ Public liability insurance declared · Est. 2026Also: House Extension · Loft Conversion · Kitchen RenovationView profile →
LGS Plumbing & Heating Ltd✓ Companies House number given · ✓ Public liability insurance declared · Est. 2011Also: Bathroom Renovation · Solar Installation · PlumbingView profile →
PCP Group✓ Companies House number given · Est. 2018Also: House Extension · Loft Conversion · Kitchen RenovationView profile →21Degree Heating Ltd✓ Companies House number given · ✓ Public liability insurance declared · Est. 2018Also: Air Conditioning Installation · Heat Pump InstallationView profile →Barry Plumbing And Heating✓ Public liability insurance declaredAlso: PlumbingView profile →Free Boiler Upgrade✓ Companies House number given · Est. 2020View profile →Thomas The Builder Ltd✓ Companies House number given · Est. 2005Also: House Extension · Loft Conversion · Kitchen RenovationView profile →Birmingham's Heating & Cooling LtdView profile →AAA Construction LtdAlso: House Extension · Loft Conversion · Kitchen RenovationView profile →All registered trades · Recent projects · Run a boilers & central heating business? Add your free profile